Sound reproducing apparatus



Nov 5, 1935. I w b. swlNYARD V 2,020,166

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SOUND REPRODUCING APPARATUS Filed March 25, 1935 ATTORNEY.

INVENTOR.

Patented Nov. 5,1935

, sormn nmonucr'so mans-ms WilliamO. swlnyarddlaysideiltfnamignortoHaseltine corporation. a corporation of Dela- A plication M as. loss,serial a... 1:351

' 10 claim. (01. lei-s1) This invention relates to an improvedhighfidelity sound reproducing apparatus andvis particularly concernedvwith sound reproducing apparatus of the type used in connection withradio 5 broadcast receivers and the like. r

,l'or'the most satisfactory reproduction of sound there must be a highdegree of fidelity of reproduction and uniformity of distribution, thatis to say, the sound waves of the various frequen- L cies must beuniformly reproduced and propagated with a uniform distributionthroughout the room or auditorium into which such waves are radiated,and there should be a uniformity of effectiveness of the various soundwaves through- 5 out the audible frequency range, without distor-- tion.

In order to obtain such satisfactory reproduc- 'tion, certain problemsare involved due to certain peculiarities in the behavior of the soundwaves 0 which are radiated by reproducers of the type now generallyused, and to effects which result from the physical nature of certainparts of the reproducing apparatus employed.

It. is a well-known phenomenon of acoustics 5 that sounds of relativelyhigh pitch. that is, sound waves of relatively short wave lengths andhigh frequencies, which are radiated from a relatively large area coneor diaphragm type of re- I producer or loudspeaker'i such as is nowgenerally used in radio-broadcastreception), as well as in someinstances from loudspeakers of the horn type (such as were formerly ingeneral use), tend to be propagated substantially as a beam. in ahead-on direction from the diaphragm,

; whereas sounds of relatively 'low' pitch, that is.

of relatively great wave lengths and low frequencies, are propagatedsubstantially spherically. The consequence of thme phenomena has been anon-uniform distribution of the sound n waves throughout the responsearea. or reoeption room, characterised by a predomination of the soundsof higher pitch in locations directly in front of the reproducimapparatus and a pre-' domination of the sounds of lower pitch in the i5adiacentlocationsr w Itisalsowellknownthatwhereasoundcav--ityorrecessisemplored;thrcughwhichsound waves are radiated from thereproducer, parallel surfaces and o'pposins'parallel so vided by suchcavity. in thepathfofthesound waves, will result, respectively.inreflections and refractions of such sound-waves. which-in turn resultin the setting up ofinterference-patterns and in norl-imiformityof-eifectlveness of the pro--v ss variouswavestbrousheuttheauiibleraseof frequencies. One explanation of these results is the tendency oftwo or more waves, which are either so reflected or' so refracted as toarrive simultaneously at the same location, to either neutralize orreinforce each other, according ,to whether .they are so related as toadd or sub- .tract at the location under consideration. The

fldelity of the reproduction of the various sound waves at differentlocations is thus affected by the inherent structural characteristics ofthe 1' sound cavity of the reproducing apparatus employed;

v his the object of this invention to provide an improved high-fidelitysound reproducing apparatus, whereby sound may be reproduced and upropagated with uniformity of distribution of the waves of variousfrequencies throughout the area into which such waves are radiated.

A further object is to provide an apparatus of. the characteraforedescribed whereby the varigo ous sound waves reproduced throughoutthe audible frequency range will be free from distortion and thefldelity of the reproduction thereof will be uniform at all locationsfor which the apparatus is designed to provide reception. g5

Various other and further objects of and ad vantages achieved by thepresent invention will be apparent from the following description takenin connection with the accompanying drawing, wherein there isillustrated, by way of an examas pie. an apparatus embodying theinvention.

. In accordance with this invention there is provided a soundreproducing apparatus which includes a sound cavity, through whichcavity a reproducing device. such as a loudspeaker of the as relativelylarge area cone or diaphragm type, is adapted to radiate sound waves. incombination with a sound wave deflector. This deflector is disposedwithin the cavity. and extends transversely across the path of the soundwaves therem through, and thereby serves to diffuse the sound waves ofrelatively higher frequencies which would otherwise tend tobe propagatedsubstantially as a beam in ahead-on direction. The deflector. thuseffects a substantially even distributim of the waves of the variousfrequencies throughout. the response area. 7

Further in accordance with this invention. the walls of the sound cavityand-theconflguration ofthedeflectoraresorelatedastoavoidpar-gooriparallel unsound cavity, thus substantially theundesirableinterference from reflections and 'refractions describedabove. 1 V lnthe luaper-u upper portion I I in a suitable well-knownmanner.

Below this apparatus a rectangular opening I! is provided in the frontwall of the cabinet, from which wall extends a sound cavity, asindicated generally by the numeral II.

The cavity ll is deflned-by a rear wall such as a baflle ll, whichslants in an upward and rearward direction from the lower edge of theopening, at an angle of approximately 10 to 20 degrees from thevertical, triangular side walls iS-il which converge rearwardly from thevertical side edges of the opening, and a top wan l8 which I slants in arearward and downward direction from the upper edge of the opening. Therear edges of the walls I! and II engage the baille I4 and aresuitabb-secured thereto, by brackets (not shown) or in any otherdesirable manner.

An opening ll is formed in the bane It at the central portion thereofand a sound reproducer or loudspeaker 2|! is disposed behind the bailleopposite the opening. The reproducer is preferably of the type having amoving coil which drives a conical diaphragm of relatively large area,its diaphragm 2| suitably engaging the bane around the margin of theopening, with its axis perpendicular to the plane of the baiiie so thatsound 'waves radiated by the reproducer will be propagated through theopening and through the sound Among other useful purposes, the soundcavity serves to provide an additional desirable amount of load on thediaphragm and to amplify the sound waves in accordance with well knownprinciples. While the sound cavity II has'been illustrated and describedas being open only at the front, it is to be understood that, in certaininstances, certain other walls, such as the side walls I, may beomitted, it only being necessary that there shall be formed a recessunconfined or semi-confined space eflective to load the soundreproducing device, and the term "sound cavity" as used herein is to beso construed. The angle of the baflle is not critical but is preferablyof such' degree that the axis of the cone will be directed towardapproximately where the head of a listener in the center of a room ofaverage size will be.

A deflector, indicated generally by the numeral 22, is provided withinthe sound recess. The deflector comprises a pair of plate-like-members23-23 cooperating to form a dihedral angle with the vertex thereofextending across the opening l9. The deflector is substantiallycoextensive with the sound cavity. The side members of the deflector maybe cut to conform to the walls of the sound cavity and so that theirfront edges lie in the plane of the front wall of the cabinet.

The dihedral angle of the deflector, while in the approved embodimentillustrated being approximately degrees, is not critical but in practicemay be varied within limits of approximately 60 to degrees. according tothe requirements 'of the particular embodiment, considering the positionof the loudspeaker in the room where the same is to be used. It iswithin the contempla-. -tion of the invention-taco construct the ballsthat its members may be adjusted to vary the. degree of theirangularity, andfor such a construction any suitable hinge or pivotingarrangement may be employed.

By virtue of the tapered effect of the deflector, 4 it .will be apparentthat pathways are provided at the sides thereof within the cavity whichare of varying width from top to bottom. Further, the shape and positionof the deflector, together with the shapesand relative angular positionsof the walls of the cavity, including the baille.

; provide a passageway, through which the sound waves are propagated,wherein there are no parallel surfaces and no opposing parallel edges.

In the operation of the apparatus, the audio- 1,

frequency or sound waves will be radiated from the diaphragm through thesound cavity, and

the waves of relatively high frequencies, which naturally would tend totravel substantially as a beam from the diaphragm, will be deflected by2 the walls of the deflector members and so diffused throughout thereceiving room as to provide a sub- I stantially even distributionthereof. By virtue of the shapes and relative positions of the various vsurfaces and edges of the sound cavity and battle, 2 there will besubstantially no interference from reflections or refractions of thewaves. The-slanting position of the bailie and the axis of the:diaphragm will serve to eflect a propagation of the sound waves in anupwardly slanting directionso 3 as to provide the maximum eflectivenessat the most desirable location, that is, in a region elevated from therelatively/low position of the reproduce-r or in aregion approximatelyat the heads of listeners in the receiving room. In the completedapparatusa loosely woven screen or tapestry may, if desired, be providedover the opening l2, to protect the deflector and cavity.

improved apparatus embodying the present invention, it will be apparentthat many and various changes and modifications may be restorted to, asto the manner of utilization of the method 4 and as to the form,structure and arrangement of the parts of the apparatus, withoutdeparting from the spirit of this invention, and it will be understoodthat all and any such changes and modiflcations are contemplated as apart of this inven- 5 tion, as defined in the appended claims.

What-is claimed is:

1. A sound reproducing apparatus comprising a sound cavity ofnon-uniform depth having an open front in a vertical plane, side wallsand a 5 rear wall slanting relative to said vertical plane,

said rear wall being provided with an opening centrally. therein, asound radiating device mounted behind said rear wall so as to radiatefront plane, said surfaces being angularly disposed so as to dispersehorizontally a beam of 6 sound radiated from said device through said 2.A sound -'reproducing apparatus comprising a sound cavity of non-uniformdepth having an open front in a vertical plane and a rear wall Iprovided with an opening centrally therein, a

soundradiating device mounted behind said rear wall so 'as to radiate abeam of sound through said opening, and a sound deflector comprisingtapered surfaces shaped t'oconform to the 11011- I uniform depth of saidcavity and having their rear edges extending across said opening andtheir front edges substantially in said front plane. said surfaces beingangularly i posed so as to disperse horizontally a beam of soundradiated from said device through said opening.

3. A sound reproducing apparatus comprising a sound cavity having anopen front in a vertical plane. side walls and a rear wall slantingrelative to said verticalplane, said rear wall being provided with anopening centrally therein. said cavity thereby being of varied depth, asound radiating device mounted behind said rear wall so as' to radiate abeam of sound through said opening, and a deflector fitted into saidcavity.

said deflector conforming to said varied depth of said cavity andproviding surfaces of tapered angular shape having longitudinal rearedges extending across said opening and front edges substantially insaid front plane and said surfaces being angularly arranged so as todisperse horisontally. a beam of sound radiated from said device throughsaid opening.

4. A sound reproducing apparatus comprising a sound cavity having an penfront in a vertical plane. rearwardly converging side walls and a rearwall slanting relative to said vertical plane and provided with anopening centrally therein, said cavity. thereby being of varied depthdiminishing from top to bottom, a sound radiating device mounted behindsaid rear wall so as to radiate a beam of sound through said opening,and

a deflector fitted into said cavity, said deflector.

conforming to said varied depth of said cavity and providing surfaces oftapered angular shape having longitudinal rear adjoining edgesextendacross said opening and front edges converging from top to bottomand disposed substantiallyin said front plane, said surfaeu beingthereby angularly arranged so as to disperse horizontally a beam ofsound radiated from said device through said opening;

' 5. A sound reproducing apparatus comprising a sound cavity symmetricalwith respect to a vertical 'plane. having an open front in a verticalplane normal to the plane of symmetry. side wallsdisposedinnon-parallelplaneaarearwallina non-vertical plane normal tothe plane of symmetry and provided with an weningcentrally therein. asound radiating device disposed behindsaidrearwallandadaptedtoradiateabeamof whereby a beam of mi radiatedfrom said device through said opening will be dispersed horisontally bysaid deflector.

6. A high-fidelity sound reproducing apparatus comprising a sound cavityincluding as the rear wall thereof a baille slanting at an angle to thevertical and, having an opening formed therein,

a sound reproducing device including a conical diaphragm disposed at therear of said cavity -with its axis Perpendicular to the plane of said isbaiiie and coincident with the center of said opening and adapted toradiate sound waves through said opening and through said-cavity; anddeflector means disposed within said cavity extending transversely ofsaid opening. is 7. A high-fidelity sound reproducing apparatuscomprising a sound cavity having a flat rear wall provided with anopening; a sound reproducing device disposed behind said rear wall andarranged to radiate sound waves said openso ing and through said cavity;and a deflector within said cavity having a pair of substantially flatsurfaces angularly arranged with adjoining edges thereof extendingtransversely of said opening.

a. A high-fidelity sound reproducing apparatus comprising a soundcavityhaving aiiatrea'rwall provided with anopening: a sound reproducingdevice disposed behind said rear wall and adapted to radiate sound wavesthrough said'opening and so through said cavity;- and a deflector havinga pair of substantially flat surfaces. an edge of one of said surfacesadjoining an edge of the other of said surfaces to provide a tapereddeflector. and said surfaces being angularly arranged with as theiradjoining edges extending transversely of 8816 e 9. A high-fidelitysound reproducing apparatus comprising a sound cavity having slantingupper, side, and rear walls. said rear wall'providing s40 sound baileand having an orifice formed there-,

in; a sound reproducing device adapted to radia'te sound waves .throughsaid opening and throwh'said cavity; and apiurality of sound wavedeflecting members angularly arranged withinsaid cavity and providing noparallel surfaces within said cavity.

10. A high-fidelity sound reproducing apparatus comprising a soundcavity having slanting upper,side,andr earwalls.saidrearwallpro-lovidingasolmdbailleandhavinganoriflceformed' therein: a sound reproducingdevice adapted to radiatesoundwavesthroughsaidweningandthroughsaidcavitnandapluralityotsound wave deflecting members arrangedwithin said cavity, with no paralleliedgesi'ormedbythewallsofsaldcavityandsaid wit-um o.

